First-Principles Study of a Zirconium-Terminated Diamond (100) Surface with Promising Negative Electron Affinity and Surface Stability

Abstract

Chemical modification of diamond surfaces generates a negative electron affinity (NEA), which shows great potential in realizing electron emission. In this study, zirconium (Zr) termination on clean and oxidized diamond (100) surfaces is theoretically proposed by using the structure prediction method, and electronic properties of these predicted surfaces are investigated by first-principles calculations. On the oxidized surfaces, the adsorption energy at 0.25 monolayer (ML) Zr coverage reaches a high value of −10.42 eV, further confirmed by the largest integrated crystal orbital Hamiltonian population value of 6.61 eV. For clean and oxidized diamond (100) surfaces, the largest NEA values at 0.25 ML Zr coverage are −3.75 eV and −3.45 eV, respectively. The dynamic stability of these surface structures is demonstrated by calculating phonon dispersion curves. Furthermore, ab initio molecular dynamics simulations confirm the high thermal stability of the oxidized diamond surface. Therefore, these results indicate that Zr-terminated diamond (100) surfaces possess good thermal stability and higher NEA, making them promising candidate materials for electron emission applications

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